My friend , known around as FFL ( younger of two wakoo brothers from Nagybecskerek ) , brought a pair of , well , pretty beaten up K3809 Tannoys ; They’re having new HF diaphragms, but surround is long ago in rock solid form …….. well above 60Hz .
There were also few more problems – suspicious bass VC centering on one at least , sorta tired cones and ugly gaskets …….
I didn’t took any pic prior to dismantling magnet assemblies from baskets , but there will be few pics of drivers from above , prior to finishing steps , so you’ll have some insight in their condition , as they arrived on my bench ……..
Read picture captions for detailed info .
I had impression that glue between magnet assembly elements is sorta dry and brittle , so I decided to put glue on circumferential joints …..
When you’re measuring anything on this (and related) type of Tannoy , it’s not unusual to have some hiccups in readings ; usual culprit for that is intermittent contact between flexi wires and awful Molex-lookalike springy contacts ; what you are gonna do is this :
Now I’m having rock solid readings of all things electrical ……
Ok , on to VC examination ; one of them was looking good , but other one not so . However – Rdc and inductance (without magnet !!) are pretty much same for both , so I was breathing much easier , realizing that darker one is still good , even if evidently having tough history …….. nothing what some care can’t put back in shape .
So – I checked VC shape on both , and worse looking (darker VC) one is slightly oval ;Few moments of fear , careful bending of Alu-former with fingers as only tool …… and VC is (mainly) properly shaped again ……..
I did the same on both bass voice coils ; after that , preparing for reassembly.
What I did in meantime is that I removed dust mesh – nitro solvent and plenty of soaking ….and patience – if you plan to have undamaged cone ; not that that is of any significance,considering that cone is going to have 2 layers of Dammar :
They’re still ugly – discolored cone and rock solid surround , one having uneven and teared gasket , second one having sky-high (fat) gasket:
Both magnets in place , so time for rejuvenating of surround and cones – explained here in details (scroll to half of page) .
HF dias in place , bass VC centering with 35Hz at 6-7mm(pp) excursion , two layers of Dammar on each bass cone , and result is as on pictures , while bass cones are again in ballpark of 35Hz Fs .